Recent hearing aids compress an input sound in accordance with a dynamic range of a hearing aid user by a digital signal process to output the compressed sound. That is, a comfortable sound is output to the hearing aid user by amplifying a small sound and decreasing a large sound. Since the sound articulation may be degraded or the uncomfortable feeling may be increased when the ambient environment noise is simultaneously amplified along with the sound, a hearing ability compensation system is changed in correspondence with the influence of ambient environment noise so as to increase an SN ratio as a ratio of a signal (sound) and noise (environment sound).
An environment adaptive type hearing aid of the related art is characterized in that a compensation method selecting section is provided to extract various feature quantities based on an input signal acquired from at least one microphone of the hearing aid so as to change a hearing ability compensation system in correspondence with the influence of ambient environment noise, compare the feature quantities with pre-registered standard patterns, select a standard pattern having the largest similarity with the input signal, and select a compensation method from a reference table in which each standard pattern is associated with a hearing compensation method (for example, see Patent Reference 1).
Patent Reference 1: JP-A-6-105399